In a wireless local area network (WLAN), each station (STA) can take a channel estimation formed between two access points (APs), and feed the information back to a controller AP, which may be a master AP, or one of the APs in collaboration. The controller AP then computes a beam-forming matrix based on the feedback. The beam-forming matrix is split into two, which is the same number as the number of APs for interference alignment (IA) to work, in the case of a two AP collaboration, but may be different with more than two APs.
There may be an Overlapped Basic Service Set (OBSS) issue where multiple APs are densely populated and there is only one large bandwidth available. That is, each AP may try to transmit the data to its own associated STA simultaneously under the same spectrum. While IA can be a solution for this issue, further development, such as IA channel estimation, is needed for IA to work in Wi-Fi.